1. Field of the Invention
The present invention relates to a printer apparatus and a laminating method for laminating, with an image protecting layer by thermal transfer, a printing medium having an image formed thereon; forming an uneven pattern on the image protecting layer; and thus providing a glossy textured finish similar to that of a silver halide photograph.
2. Description of the Related Art
Examples of printing methods include a thermal transfer printing method in which an image is formed by thermally transferring color materials, such as dyes, from a thermal transfer sheet onto a recording medium. For protecting the image formed on the recording medium, the thermal transfer printing method further involves formation of a transparent image-protecting layer on the image. The thermal transfer printing method uses a density gradation method which allows free control of image density. Therefore, it is possible to provide a high-quality image close to a silver halide photograph, which is excellent in gradation characteristic and color reproducibility.
The thermal transfer printing method is expected to provide not only a high-quality image close to a silver halide photograph, but also a finish close to that of a silver halide photograph. Typically, silver halide photographs are available in glossy and textured finishes, and users select one of them according to their preferences. Recently, however, there have been demands for a printed material with a surface that is both glossy and textured.
Examples of techniques for achieving a textured finish using the foregoing thermal transfer printing method are disclosed in Japanese Patent No. 3185254, Japanese Unexamined Patent Application Publication No. 2006-182012, Japanese Patent No. 3021490, and Japanese Patent No. 3861293.
Japanese Patent No. 3185254 discloses a technique in which, after embossing (like texturing) is performed using an embossing roll or the like on a polyolefin resin layer on the surface of base paper, the surface roughness of printing paper coated with an absorbing layer is defined. Such printing paper, which originally has high surface roughness, will not firmly adhere to an ink ribbon and heating elements of a printer head during printing. This may cause occurrence of unprinted spots on the printing paper after printing, and thus may cause degradation in print quality.
Japanese Unexamined Patent Application Publication No. 2006-182012 discloses a technique in which, after transfer of an image protecting layer to printing paper, the surface of the image protecting layer is embossed under heating conditions by an embossing roll with surface irregularities, so that a matte pattern is formed on the resulting surface after printing. However, if the printing paper is embossed under non-heating conditions, cracks may be produced in the image protecting layer on the surface of the printing paper or in an absorbing layer, and thus lightfastness of the printing paper may be degraded. To prevent such cracks, it is necessary to emboss the printing paper while heating it. This involves heating of the embossing roll to at least a glass transition temperature (Tg) of the image protecting layer (e.g., at least about 100° C.). Additionally, it is necessary to apply embossing pressure to the printing paper. This involves use of a large embossing device, which may not be easily accommodated in the main body of the printer. Therefore, it is difficult to form an uneven pattern on the image protecting layer in a short time after printing.
Japanese Patent No. 3021490 discloses a technique in which, during formation of an image protecting layer, the amount of thermal energy continuously applied to heating elements is varied continuously or stepwise every predetermined distance. Thus, regions of different gloss levels can be arranged in any order on the surface of the image protecting layer. With this method, it becomes not necessary to provide a special device inside the printer. Additionally, this method allows the user to select a desired finish, such as a glossy finish or a textured finish, and there is little difference in printing time between finishes.
Japanese Patent No. 3861293 discloses a technique where a memory in which an uneven pattern is recorded is provided, uneven-pattern data for each printing line is generated during transfer of an image protecting layer, and the amount of voltage applied to a thermal transfer head is varied, so that a desired uneven pattern is formed.
However, a method for forming such an uneven pattern is only described as “regions of different heights are arranged in any order on the surface of the image protecting layer” in Japanese Patent No. 3021490, and “random pattern data serving as a minimum unit can be generated by any method” in Japanese Patent No. 3861293. That is, there has been no specific discussion about a method for forming an uneven pattern for providing a glossy textured finish.